Hi Dennis,
On 20/07/2016 13:43, Dennis Chen wrote:
> Hi Eric,
> Some small questions/comments below:
>
> On Tue, Jul 19, 2016 at 12:55:07PM +0000, Eric Auger wrote:
>> iommu_get/put_msi_cookie allocates/frees the resource used to store
>> and ref count the MSI doorbell mappings. iommu_msi_set_aperture
>> initializes the iova domain used for MSI IOVA allocation and sets the
>> iommu domain's msi geometry.
>>
>> The implementation relies on dma-iommu API and iova API.
>>
>> New msi functions are fully implemented if CONFIG_IOMMU_MSI is set.
>>
>> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
>>
>> ---
>> v10:
>> - split error management in iommu_msi_set_aperture
>>
>> v9:
>> - remove is_aperture_set and use iommu_domain_msi_aperture_valid helper
>> instead
>> - set iommu domain's msi geometry
>>
>> v8:
>> - new design where msi-iommu relies on dma-iommu
>> - remove the iommu_domain * from the doorbell_mapping struct
>> - added is_aperture_set
>>
>> v7:
>> - fix locking
>> - add iova_cache_get/put
>> - static inline functions when CONFIG_IOMMU_DMA_RESERVED is not set
>> - introduce struct reserved_iova_domain to encapsulate prot info &
>> add prot parameter in alloc_reserved_iova_domain
>>
>> v5 -> v6:
>> - use spin lock instead of mutex
>>
>> v3 -> v4:
>> - formerly in "iommu/arm-smmu: implement alloc/free_reserved_iova_domain" &
>> "iommu: add alloc/free_reserved_iova_domain"
>>
>> v2 -> v3:
>> - remove iommu_alloc_reserved_iova_domain & iommu_free_reserved_iova_domain
>> static implementation in case CONFIG_IOMMU_API is not set
>>
>> v1 -> v2:
>> - moved from vfio API to IOMMU API
>> ---
>> drivers/iommu/Kconfig | 7 ++++
>> drivers/iommu/Makefile | 1 +
>> drivers/iommu/msi-iommu.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++
>> include/linux/msi-iommu.h | 65 ++++++++++++++++++++++++++++++
>> 4 files changed, 173 insertions(+)
>> create mode 100644 drivers/iommu/msi-iommu.c
>> create mode 100644 include/linux/msi-iommu.h
>>
>> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
>> index ad08603..5ea1610 100644
>> --- a/drivers/iommu/Kconfig
>> +++ b/drivers/iommu/Kconfig
>> @@ -74,6 +74,11 @@ config IOMMU_DMA
>> select IOMMU_IOVA
>> select NEED_SG_DMA_LENGTH
>>
>> +# IOMMU MSI mapping
>> +config IOMMU_MSI
>> + bool
>> + select IOMMU_DMA
>> +
>> config FSL_PAMU
>> bool "Freescale IOMMU support"
>> depends on PPC_E500MC || (COMPILE_TEST && PPC)
>> @@ -296,6 +301,7 @@ config SPAPR_TCE_IOMMU
>> config ARM_SMMU
>> bool "ARM Ltd. System MMU (SMMU) Support"
>> depends on (ARM64 || ARM) && MMU
>> + select IOMMU_MSI
>> select IOMMU_API
>> select IOMMU_IO_PGTABLE_LPAE
>> select ARM_DMA_USE_IOMMU if ARM
>> @@ -309,6 +315,7 @@ config ARM_SMMU
>> config ARM_SMMU_V3
>> bool "ARM Ltd. System MMU Version 3 (SMMUv3) Support"
>> depends on ARM64 && PCI
>> + select IOMMU_MSI
>> select IOMMU_API
>> select IOMMU_IO_PGTABLE_LPAE
>> select GENERIC_MSI_IRQ_DOMAIN
>> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
>> index c6edb31..a381e66 100644
>> --- a/drivers/iommu/Makefile
>> +++ b/drivers/iommu/Makefile
>> @@ -2,6 +2,7 @@ obj-$(CONFIG_IOMMU_API) += iommu.o
>> obj-$(CONFIG_IOMMU_API) += iommu-traces.o
>> obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o
>> obj-$(CONFIG_IOMMU_DMA) += dma-iommu.o
>> +obj-$(CONFIG_IOMMU_MSI) += msi-iommu.o
>> obj-$(CONFIG_IOMMU_IO_PGTABLE) += io-pgtable.o
>> obj-$(CONFIG_IOMMU_IO_PGTABLE_ARMV7S) += io-pgtable-arm-v7s.o
>> obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE) += io-pgtable-arm.o
>> diff --git a/drivers/iommu/msi-iommu.c b/drivers/iommu/msi-iommu.c
>> new file mode 100644
>> index 0000000..de02ede
>> --- /dev/null
>> +++ b/drivers/iommu/msi-iommu.c
>> @@ -0,0 +1,100 @@
>> +/*
>> + * Reserved IOVA Management
>> + *
>> + * Copyright (c) 2015 Linaro Ltd.
>> + * www.linaro.org
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + *
>> + */
>> +
>> +#include <linux/iommu.h>
>> +#include <linux/dma-iommu.h>
>> +#include <linux/msi-iommu.h>
>> +#include <linux/spinlock.h>
>> +#include <linux/iova.h>
>> +
>> +struct doorbell_mapping {
>> + struct kref kref;
>> + struct list_head next;
>> + phys_addr_t addr;
>> + dma_addr_t iova;
>> + size_t size;
>> +};
>> +
>> +struct doorbell_mapping_info {
>> + struct list_head list; /* list of doorbell mapping entries */
>> + spinlock_t lock;
>> +};
>> +
>> +int iommu_get_msi_cookie(struct iommu_domain *domain)
>> +{
>> + struct doorbell_mapping_info *dmi;
>> + int ret;
>> +
>> + if (domain->msi_cookie || domain->iova_cookie)
>> + return -EINVAL;
>> +
>> + ret = iommu_get_dma_cookie(domain);
>> + if (ret)
>> + return ret;
>> +
>> + dmi = kzalloc(sizeof(*dmi), GFP_KERNEL);
>
> if dmi == NULL here,
>
>> +
>> + INIT_LIST_HEAD(&dmi->list);
>> + spin_lock_init(&dmi->lock);
>
> will the above 2-line codes triger kernel NULL pointer dereference panic message?
> if so why don't we check dmi immediately after the kzalloc call like this:
Yes definitively. Thanks for spotting the oversight!
Regards
Eric
>
> dmi = kzalloc(sizeof(*dmi), GFP_KERNEL);
> domain->msi_cookie = dmi;
> if (!dmi)
> return -ENOMEM;
>
>> + iova_cache_get();
>
> return iova_cache_get();
>> +
>> + domain->msi_cookie = dmi;
>> +
>> + return dmi ? 0 : -ENOMEM;
>> +}
>> +EXPORT_SYMBOL(iommu_get_msi_cookie);
>> +
>> +void iommu_put_msi_cookie(struct iommu_domain *domain)
>> +{
>> + struct doorbell_mapping_info *dmi = domain->msi_cookie;
>> +
>> + if (!dmi)
>> + return;
>> +
>> + domain->msi_cookie = NULL;
>> +
>> + WARN_ON(!list_empty(&dmi->list));
>> +
>> + kfree(dmi);
>> + iommu_put_dma_cookie(domain);
>> + iova_cache_put();
>> +}
>> +EXPORT_SYMBOL(iommu_put_msi_cookie);
>> +
>> +int iommu_msi_set_aperture(struct iommu_domain *domain,
>> + dma_addr_t start, dma_addr_t end)
>> +{
>> + struct doorbell_mapping_info *dmi = domain->msi_cookie;
>> + int ret;
>> +
>> + if (!dmi)
>> + return -ENODEV;
>> +
>> + if (iommu_domain_msi_aperture_valid(domain))
>> + return -EINVAL;
>> +
>> + ret = iommu_dma_init_domain(domain, start, end - start + 1);
>> +
>> + if (!ret) {
>> + domain->msi_geometry.aperture_start = start;
>> + domain->msi_geometry.aperture_end = end;
>> + }
>> +
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(iommu_msi_set_aperture);
>> +
>> diff --git a/include/linux/msi-iommu.h b/include/linux/msi-iommu.h
>> new file mode 100644
>> index 0000000..392aa6f
>> --- /dev/null
>> +++ b/include/linux/msi-iommu.h
>> @@ -0,0 +1,65 @@
>> +/*
>> + * Copyright (c) 2015 Linaro Ltd.
>> + * www.linaro.org
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + *
>> + */
>> +#ifndef __MSI_IOMMU_H
>> +#define __MSI_IOMMU_H
>> +
>> +#include <linux/types.h>
>> +#include <linux/kernel.h>
>> +
>> +struct iommu_domain;
>> +
>> +#ifdef CONFIG_IOMMU_MSI
>> +
>> +/**
>> + * iommu_get_msi_cookie - Acquire MSI mapping resources for a domain
>> + * @domain: IOMMU domain to prepare for MSI mapping
>> + *
>> + * IOMMU drivers which require MSI mapping should normally call this
>> + * from their domain_alloc callback when domain->type ==
>> + * IOMMU_DOMAIN_UNMANAGED.
>> + */
>> +int iommu_get_msi_cookie(struct iommu_domain *domain);
>> +
>> +/**
>> + * iommu_put_msi_cookie - Release a domain's MSI mapping resources
>> + * @domain: IOMMU domain previously prepared by iommu_get_msi_cookie()
>> + *
>> + * IOMMU drivers requesting MSI mapping should normally call this from
>> + * their domain_free callback.
>> + */
>> +void iommu_put_msi_cookie(struct iommu_domain *domain);
>> +
>> +/**
>> + * iommu_msi_set_aperture: allocate the msi iova domain
>> + * according to the specified start/end IOVAs
>> + *
>> + * @domain: iommu domain handle
>> + * @start: MSI iova start address
>> + * @end: MSI iova end address
>> + */
>> +int iommu_msi_set_aperture(struct iommu_domain *domain,
>> + dma_addr_t start, dma_addr_t end);
>> +
>> +#else
>> +
>> +static inline int
>> +iommu_msi_set_aperture(struct iommu_domain *domain,
>> + dma_addr_t start, dma_addr_t end)
>> +{
>> + return -ENOENT;
>> +}
>> +
>> +#endif /* CONFIG_IOMMU_MSI */
>> +#endif /* __MSI_IOMMU_H */
>> --
>> 1.9.1
>>
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>>
>
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